Light-emitting devices such as light-emitting diodes (LEDs) are electrical devices that emit electromagnetic radiation in the form of visible light when a voltage is applied across an active region of the LED between an anode and a cathode. LEDs typically comprise one or more layers of semiconductor material, within which electrons supplied from the anode and holes supplied from the cathode recombine. As the electrons and holes recombine within the active region of the LED, energy is released in the form of photons, which are emitted from the active region of the LED.
LEDs may be fabricated to include a wide range of different types of semiconductor materials including, for example, III-V semiconductor materials, and II-V semiconductor materials. The wavelength of the light emitted from any particular LED is a function of the amount of energy released when an electron and a hole recombine. Thus, the wavelength of the light emitted from the LED is a function of relative difference in energy between the energy level of the electron and the energy level of the hole. The energy levels of the electrons and the energy levels of the holes are at least partially a function of the composition of semiconductor materials, the doping type and concentration, the configuration (i.e., crystal structure and orientation) of the semiconductor materials, and the quality of the semiconductor materials within which recombination of the electrons and holes occurs. Thus, the wavelength of the light emitted from an LED may be selectively tailored by selectively tailoring the composition and configuration of the semiconductor materials within the LED.
In is known in the art to fabricate LEDs that comprise III-V semiconductor materials, such as Group III nitride materials. Such Group III nitride LEDs are known to be capable of emitting radiation in the blue and green visible regions of the electromagnetic radiation spectrum, and are known to be capable of operating at relatively high power and luminosity.